The objective of this research project is to develop and perfect methods of obtaining fluorescently labelled heavy meromyosin, tropomyosin, troponin, actin and C-protein so that these fluorescent protein tracers can be used to localize actin and myosin filaments in non-muscle cells. This novel approach to understanding cell motility has proven feasible in pilot studies by the applicant. The sensitivity of the method permits protein localization in situ on a light microscopic level and can be further refined by electron microscopic observation. The techniques necessary for this work are 1) protein chemistry, 2) microscopy: fluorescence, phase, polarizing and electron, 3) tissue culturing, 4) micromanipulation. The proteins which will be isolated, purified and labelled with fluorescein isothiocyanate bind specifically with either myosin or actin thin filaments. Dividing cells will be labelled with these fluorescent proteins during different stages of the cell cycle in order to observe the changing patterns of actin and myosin localization. Similar observations will be carried out on amoeboid cells during pseudopod formation and retraction. Microinjection of fluorescent monomer actin will be attempted in order to observe actin utilization during different stages of cell division and amoeboid locomotion. Cancerous cells will be compared with control cells for patterns of actin localization, especially under conditions where contact inhibition prevails for normal cells. If marked differences are found, these fluorescent agents could then be used as inexpensive and sensitive diagnostic agents.